Multiple fuse plug



Ott. 15, 1935. 1 Bl GLOWACKl v 2,017,489

MULTIPLE FUSE PLUG Filed Jan. 22, 1954 2 Sheets-Sheet l Oct. 15, 1935.JfB. GLowAcKl 2,017,489

n MULTIPLE FUSE PLUG iled Jan. 22, 1954 2 Sheets-Sheet 2 Patented Oct.15, 1935 UNITED STATES PATENT OFFICE MULTIPLE FUSE PLUG 19 Claims.

The present invention relates to a multiple screw type fuse plug havinga spring controlled contact head for resiliently holding the contact pinseated in any one of a plurality of contact sockets which are connectedwith the inner ends of a plurality of radially directed fuse elementswhich, in one form of the invention, are positioned in a renewablemultiple fuse supporting barrel unit which is removably clamped on ascrew type base plug.

Itis an object of this invention to provide a multiple type of fuse plugwhich is so constructed that a single contact member may be selectivelyset to connect up with any one of a plurality of fuse elements engagedwithin the fuse plug.

It is also an object of this invention to provide a multiple screw typefuse plug having a renewable type of fuse carrying barrel whereby a newmultiple type of fuse and a supporting n barrel may be engaged between aplug unit and contact head when the rst series of fuse elements havebeen used.

It is a further object of this invention to provide a multiple screwtype fuse plug having a plurality of visible fuse elements so positionedthat any one of the elements may be selectively connected in a circuitby means of an adjustable contact means.

It is furthermore an object of this invention to provide an improvedtype of multiple fuse plug having a ring fuse unit provided with aplurality of radially directed fuse elements, any one of which isadapted to be connected in a circuit by means of a spring controlledadjustable contact member. Y

Another object of the invention is to provide a multiple screw type fuseplug wherein a plurality of radially positioned fuse elements areengaged by means of a plurality of contact sockets secured in order in adisc to permit a contact pin carried by a spring-controlled rotatableknob or head to be removably engaged in any one of the contact socketsfor the purpose of selectively connecting up one of the fuse elements ina circuit.

It is an important object of this invention to provide an improved typeof a multiple fuse plug wherein a renewable barrel containing aplurality of fuse elements is removably engaged between a screw baseplug and a head which is rotatable to permit a contact member to beselectively moved into engagement with any one of the fuse elementsuntil all of the fuse elements have been blown, after which therenewable (Cl. ZOU-125) barrel may be replaced by a new one containing anew set of fuse elements.

Other and further objects of this invention will be apparent from thedisclosures in the accompanying specication and drawings.

The invention (in a preferred form) is illustrated in the drawings andhereinafter more fully described.

On the drawings:

Figure 1 is an elevational View of a multiple screw type fuse plugembodying the principles of this invention.

Figure 2 is an enlarged top plan View of the fuse plug.

Figure 3 is an enlarged longitudinal middle section of the fuse plugwith parts shown in ele- Vation.

Figure 4 is a transverse sectional View taken on line IV--IV of Figure3, to show the fuse ring unit constructed of a plurality of fuseelements. 20

Figure 5 is a modified form of multiple fuse element unit in the form ofa continuous ring having a plurality of radially disposed fuse elementsintegrally formed thereon.

Figure 6 is a sectional detail view taken on line VI--VI of Figure 3 andillustrating the bottom view of the contact head of the fuse plug.

Figure '7 is an enlarged fragmentary detail section of the fuse plugtaken on line VII- VII of Figure 2 with parts shown in elevation.

Figure 8 is a top plan view of the apertured supporting disc forcarrying the contact sockets in position between the fuse elements andthe contact pin of the fuse plug.

Figure 9 is a transverse detail section taken on line IX-IX of Figure 8and showing one of the contact sockets projecting upwardly above the topsurface of the supporting disc.

Figure l0 is a side elevation of the flanged contact sleeve or ferruleremoved from the removable fuse barrel unit of the fuse plug.

Figure 11 is a sectional view of the fuse plug similar to thatillustrated in Figure 4 but having the fuse elements removed.

Figure l2 is a longitudinal central sectional view of a modiiied form ofmultiple screw type fuse plug, of a type in which the entire fuse plugmust be replaced when the plurality of fuse elements have been blown.

As shown on the drawings:

The improved multiple screw type fuse plug comprises a base or plugsection I constructed of insulating material and having integrallyformed around the upper portion thereof an outwardly extending knurledflange 2.

Seated around the lower portion of the base plug I is a spirallythreaded sleeve or screw shell 3, the outer end of which is ilangedinwardly and is molded into the material forming the base plug I.Integrally formed on the inner end of the screw shell 3 is a ring orsleeve 4 which is also molded into the material forming the base plug Iand projects upwardly and has the end thereof bent inwardly to provide acontact flange 5 which is disposed against the top surface of the baseplug I as clearly illustrated in Figs. 3 and 7. A recess or pocket 6 isformed in the upper central portion of the base plug I and is alsoprovided with an axial passage in which the enlarged end 'I of a guideand connecting sleeve is secured. The enlarged section 'I of the tubularsleeve is provided with a knurled section 8 to hold the sleeve againstrotation within the base plug. An upper sleeve section 9 is integrallyformed with the lower section I and is formed with an intermediatethreaded portion I0. The reduced section 9 of the connecting sleeveprojects upwardly above the upper end of the base plug I through therecess or pocket 6.

Slidably projecting through the sleeve section 9 is a contact post II,the lower end of which is positioned to project into the enlarged sleevesection I and has 'engaged therearound a control spring I2 the inner endof which seats against a. shoulder within the sleeve section I while theouter end of said spring seats against the head I3 of a screw I4 whichis removably threaded into a threaded opening in the lower end of thecontact post II, as clearly illustrated in Figure 3. Secured in thelower end of the sleeve section I is a tubular contact head I5 providedat its outer end with a retaining flange I6 which serves to hold aninsulation washer I'I in position around an extending portion of thesleeve section I and in contact with the lower end surface of the baseplug I as clearly illustrated in Figure 3.

Removably secured or clamped against the flange 5 on the inner end ofthe base plug I is a renewable barrel unit in which the fuse elements ofthe fuse plug are carried. The renewable barrel unit comprises a body orcore I8 formed of a suitable insulating material which is molded to formand has a ring of chambers or pockets I9 and a plurality of radiallypositioned seats or depressions 20 which project inwardly from the topsof the inner sides of the chambers I9, as clearly illustrated in Figure11. Each of the depressions 29 is provided with a hole 2 I. As alsoshown in Figure l1, a circular seat 23 is provided in the top of thebarrel core unit I8 to receive a top contact flange 24 seated therein.The contact flange 24 is integrally formed on the upper end of aconducting sleeve or collar 25 having a plurality of binding openings 26formed therein as clearly illustrated in Figure 10. The conductor sleeve25 is molded in the material forming the barrel core unit I8 and issecurely bound in position by means of the insulating material fillingin the openings 26 to bind the conductor sleeve 25 in pla'ce. Integrallyformed on the lower end of the conductor sleeve 25 is an inwardlydirected lower contact flange 21 which is so positioned that it willtightly seat against the Contact flange 5 of the base plug as clearlyillustrated in Figure 3.

The barrel core unit I8 is provided on its lower end with an internallythreaded extension or collar 28 which, when the barrel unit is inposition upon the base plug, projects into the charnber 6 and isthreaded downwardly on the threaded section I0 of the coupling sleeve orconnector which is secured axially within the base plug I. The renewalbarrel may thus be threaded downwardly on the threaded sleeve III untilthe lower contact flange 2'I of the barrel unit is brought into tightcontactwith the upper 5 contact ange 5 of the base plug.

Formed around themolded barrel core I8 is a metal casing or housing 29the outer peripheral surface of which is knurled as clearly illustratedin Figure 1. The casing 29 is provided with a l0 plurality of ventopenings or holes 30 positioned to communicate with the space above thetop surface of the core I8 of the barrel unit.l The lower margin of thebarrel casing 29 is deflected inwardly beneath the bottom surface of thecore lo I8 and then downwardly to provide a supporting flange 3| whichprojects into a peripheral groove provided in the upper portion of thebase plug above the base plug flange 2 as clearly illustrated in Figure3. In the renewable barrel unit 20 above the explosion chambers I9 are aplurality of fuse units or elements each comprising a segment-shapedsection 32. an apertured head section 33 and a reduced or restrictedmelting strip or stem 34 which integrally connects the sections 25 32and 33 as clearly illustrated in Figure 4. The various fuse elements arepositioned with the segment-shaped sections arranged adjacent oneanother to form a ring having the melting strips 34 projecting radiallyinwardly with the head 30 sections 33 of the fuse elements seated in thereceiving recesses or depressions 20 (Figure 11) so that the openings orapertures in the head sections 33 register with the holes 2| provided inthe core I8 of the renewable barrel. The fusing 3 strips 34 are sopositioned that they project diametrically across the tops of theexplosion chambers I9. Seated within the upper portion of the circularrecess or groove 23 of the barrel core I8 above the shanks orsegment-shaped portions 32 40 of the fuse elements is a circular berwasher 35.

Seated in the barrel casing 29 upon the upper end of the barrel core I8and upon the filler or washer 35 is a circular fiber plate or disc 36having a plurality of sight openings 3'I arranged 45 in a circle asclearly illustrated in Fig. 8. 'I'he bei' plate 36 is also provided witha circular arrangement of openings to the inside of the openings 31 andhave secured therein a plurality of contact sockets 38 each of which isprovided 50 with a downwardly projecting contact pin or stem 39. Asillustrated in Figure 9, it will be noted that one or more of thecontact sockets 38 project above the top surface of the disc or plate 36to permit the same to project into aper- 55 tures 40 (Figure 3) providedin a clear mica window disc 4I seated on the top surface of the fiberplate 36. The projection of one or more of the projecting ends of thecontact sockets 38 into the openings 40 of the mica disc 4I holds 00said disc against rotation. As illustrated In Figure 3, the upper marginof the barrel casing 29 is deflected inwardly to form a retaining ilange42. As clearly illustrated in Figure 8, the fiber plate 36 is providedwith a central opening 43 05 which registers with a central opening inthe mica disc 4I to permit the plate and said mica disc to be engagedover the upper end of the reduced section 9 of the locking .sleeve whichbolts the renewable barrel to the base plug of 70 the device.

The contact post II projects upwardly through the renewable barrel unitand is provided with a diametrical passage in which the arm or shankportion 44 0f a contact finger or pin 45 projects. 75

'I 'he contact pin 45 and its shank 44 are molded within a contact heador knob 46 which in turn is molded on the upper perpiherally grooved endof the contact post II. The contact head or knob 45 is provided with aperipherally knurled ange 4l' to facilitate turning of the head or knobwhen the same is pulled slightly upwardly against the action of thespring I2 to permit the contact point 45 to be engaged through theapertured mica disc into any one of the contact sockets 38.

Figure 12 illustrates a modified form of multiple screw type fuse plugin which the parts which are identical with the parts of the fuse plugas described in connection with Figures 1 to l1 inclusive, aredesignated with corresponding reference numerals.

In the modined form of fuse plug the reference numeral 48 indicates aplug core or body constructed of insulation composition matter. The coreor body 46 is provided in its upper end with a circular row of explosionpockets or chambers 49 while the lower end of the body is provided witha circular row of depressions or holes 50. Molded axially in the body orcore 48 is a guide tube or sleeve comprising an enlarged lower tubularsection 5| and an integral reduced upper section 52, the upper end ofwhich projects upwardly above the upper end of the body 48 throughseveral openings provided in the insulation plate 36 and in the 'cawindow or disc 4I. The exterior surface of the lower cylindrical section5| of the axial sleeve is provided with a knurled surface 53 whichserves to act as a binding means for holding the guide sleeve inposition against movement with respect to the body 48. The core or body48 is molded within a casing or housing 54 with the'upper end of thehousing projecting in or being molded within the material forming theupper part of the core. The embedded upper end of the housing 54 has theupper margin thereof deflected outwardly to provide a contact flange 55.Formed in the upper embedded portion of the housing 54 are a pluralityof apertures or openings 55 which serve as a binding means permittingthe material forming the core or body 48 to seat in said openings tohold the upper flanged portion of the body 48 securely in place. Theupper end oi the core or body 48 is also provided with fuse elementdepressions or seats 20, the holes 2| and the grooves 23 similar to thearrangement illustrated in Figure 11 of the drawings.

Engaged around the upper flange portion of the core or body 48 is anexternally knurled retaining collar 51 constructed of metal. The metalretaining collar 5'I is provided with a plurality of vent openings 58positioned at substantially the level of the top surface of the body 48in order to permit the escape of gases and the like from the combustionchambers 49 outwardly between the top surface of the body 48 and thebottom surface of the plate 36.

The lower margin of the collar 51 is deflected inwardly to form a lowerretaining ange 59 and the upper margin of the collar 51 is deflectedinwardly to provide a top retaining ange 66 for holding the insulationplate 35 and the mica disc 4I in position.

Slidably engaged in the guide sleeve of the fuse plug is the contactpost I-I having the contact head 46 molded thereon, similar to thearrangement illustrated in Figure 3. The contact head 46 has embeddedtherein the contact pin 45 which is adapted to be selectively engaged inany one of the plurality oi' contact sockets 33. The contact head 46 isresiliently held in position against the top surface of the mica window4I by means of a coiled spring and a headed screw member similar to thearrangement illustrated in Figure 3.

'I'he lower margin of the casing or housing 54 is deflected inwardly toprovide a bottom retaining iiange 6| which is provided with a pluralityof openings which register with the holes 56. Securely engaged aroundthe lower reduced portion of the housing 54 is a shell 62 the upper endoi which seats against a shoulder 63 forming a part of the housing 54while the lower end of the screw base is deflected inwardly to provide aretaining flange 64 having a plurality of round or cylindrical sleevesor shells 65 struck inwardly therefrom to project through the openingsin the base flange 6| and into the body recesses or holes 50.

Secured in the lower end oi the guide sleeve section 5| isa angedcontact head 66 which holds an insulation washer 6l in position againstthe lower retaining flange 64 of the screw base 62.

Figure 5 of the drawings illustrates a modifled form of fuse elementunit which, if desired, may be used in place of the plurality ofradially arranged fuse elements 32-33-34 illustrated in Figure 4. Themodified form of fuse element unit comprises a continuous fuse ring 68havingintegrally formed on the inner margin thereof a plurality ofinwardly or radially directed fusing or melting sections 69 terminatingin fuse eleelement heads 'I6 provided with apertures 7|.

The operation of the fuse plug is as follows:

With a loaded renewable fuse barrel engaged on the threaded portion IIIof the guide sleeve and with the contact post I I and contact head 46 inposition as illustrated in Figure 1, the screw base 3 is screwed into afuse plug socket by means of the knurled flange 2 until the contact headI6 is brought into contact with the contact member within the fuse plugsocket. With the contact pin 45 engaged in one of the contact sockets 38one of the fuse elements 34 is properly connected in the electriccircuit.

When a short circuit condition is encountered, or when an excessiveamount of current passes through the circuit, the fuse element 34connected up in the circuit will melt or blow into the explosion chamberI9 beneath the fuse element and the products of combustion resultingfrom the blowing of the fuse are permitted to escape upwardly betweenthe top surface of the barrel core I8 and the insulation plate 36outwardly through the vent holes 30.

By looking through the mica windows 4| an attendant can easily tellwhich of the fuses has been blown and if the fuse in circuit has beenblown it is only necessary for the operator to pull outwardly on thecontact head 46 against the action of the spring I2 to move the contactpin 45 out'of contact with the contact socket 38 of the blown fuseelement. By rotating the contact head 46 when raised, the contact pin 45may be lowered into another contact socket 38 with the pin projectingthrough the respective opening 46 provided in the mica window 4|. Inthis manner a good or unblown fuse element is connected in circuit. Whenall of the fuse elements contained within the renewable barrel have beenblown, the fuse plug is removed from its socket and a screw driver maybe inserted through the contact head sleeve I5 to engage the screw headI3 to rotate the same thereby forcing out the contact head or ferrule I5and at the same time releasing the contact post I I to allow said postand the contact head 46 to be removed. With the removal of the contactpost and head the used renewable fuse barrel unit is unthreaded from thethreaded section I0 of the axial sleeve and is replaced by means of anew barrel unit containing a set of new fuse elements. It Will of coursebe understood that the fuse elements contained in the renewable barrelmay be of a type illustrated in Figure 4 or of the unitary multipleelement type illustrated in Figure 5.

In the form of fuse plug illustrated in Figure 12, there is no renewablefuse element barrel so that when all of the fuse elements of this typeof fuse plug have been blown, it is, of course, necessary to replace theentire fuse plug by a new one.

It will, of course, be understood that various details of constructionmay be varied through a wide range without departing from the principlesof this invention, and it is, therefore, not the purpose to limit thepatent granted hereon otherwise than necessitated by the scope of theappended claims.

I claim as my invention:

1. A multiple screw type fuse plug comprising a screw type body unit, acontact sleeve unit therein, a spring controlled contact post slidablymounted in the sleeve unit. a head formed on the projecting end of thecontact post, a. plurality of fuse elements in said body unit, anapertured plate engaged against one end of the body unit, a plurality ofcontact sockets in said plate and engaging the fuse elements, anapertured transparent disc engaged against one side of said plate, and acontact member connected With the contact post and projecting from thecontact head through the apertured transparent disc into contactingengagement with a selected one of said contact sockets.

2. A multiple screw type fuse plug comprising a body unit, an aperturedscrew shell engaged thereon, a plurality of apertured fuse elements inthe body unit and communicating with the screw shell, a plurality ofcontact sockets arranged to project through the fuse elements, atransparent covering having openings therein to nt over said contactsockets, and contact means movable longitudinally and rotatably withrespect to the body unit for selective removable engagement with any oneof said contact sockets.

3. A multiple screw type fuse plug comprising a base, a contact sleevesecured thereto and projecting therefrom, a barrel unit removablyengaged on the contact sleeve in contact with the base unit, a pluralityof fuse elements in the barrel unit, a plate secured in the barrel unit,a plurality of contact sockets supported by the plate and havingcontacting engagement with the fuse elements, an apertured transparentdisc in the barrel unit covering said plate with the apertures in thedisc registering with the contact sockets, a spring controlled contactpost slidably and rotatably engaged in said sleeve, a contact headsecured on the projecting end of the contact post and disposed to theoutside of the transparent disc, and a contact member in the contacthead for removable engagement with any selected one of the contactsockets when the contact post and the contact head are movedlongitudinally and rotatably with respect to the barrel unit.

4. A multiple screw type fuse plug comprising a base unit, a screw shellengaged thereon and projecting into the base unit and having a.plurality of openingstherein for binding different portions of the baseunit together, a. sleeve secured in the base unit and projectingtherefrom, an insulation washer engaged on one projecting end of thesleeve and in contact with one end of the base unit, a contact meansengaged in the sleeve for holding the insulation washer in position, abarrel unit having al plurality of explosion chambers therein, saidbarrel unit removably engaged on the sleeve in contact with the screwshell, a plurality of fuse elements in the barrel unit, apertured meansembedded in the barrel unit and affording a contact between the fuseelements and the screw shell of the base unit, an insulation plate inthe barrel unit, a plurality of contact sockets in the insulation platehaving contacting engagement with the fuse elements, an aperturedtransparent disc in the barrel unit covering the insulation plate andhaving the apertures registering with said contact sockets, a. springcontrolled contact post slidably and rotatably engaged in the sleeve andprojecting through the barrel unit, a contact head on the contact post,and a contact pin connected with the contact post and partially embeddedin the contact head, said contact pin projecting from the contact headinto a selected removable position in contact with one of the contactsockets.

5. A multiple screw type fuse plug comprising a screw base unit, achambered barrel unit removably engaged with the base unit and havingvent openings therein, a plurality of fuse elements in the barrel unit,a plurality of contact members in the barrel unit connected with thefuse elements, an apertured transparent disc in the barrel unit havingthe apertures thereof registering with the contact members, a springcontrolled contact unit slidably and rotatably engaged with the baseunit and with the barrel unit, and a contact pin carried by the contactunit for selective engagement through the openings in the transparentdisc for contact with a selected contact member and the fuse elementconnected therewith.

6. A multiple fuse plug comprising a body unit, a contact unit slidablyand rotatably connected therewith, a wheel type fuse element comprisinga plurality of fuse members engaged in the body unit, and contactsockets projecting through the fuse members for selective engagement bythe contact unit when the contact unit is pulled outwardly and rotated.

7. A multiple fuse plug of the class described including in combinationa fuse unit comprising a radially split rim section having a pluralityof apertured fusing members radially projecting ln- Wardly therefrom andterminating short of the center.

8. A multiple fuse plug of the class described including in combinationa. body unit, a wheel type fuse unit therein comprising a circular rimsection having a plurality of apertured fuse members radially formedthereon, contact sockets projecting through the apertured fuse members,and an adjustable contact means connected with the body unit andlongitudinally and rotatably movable into selective telescopicengagement with the contact sockets.

9. A multiple fuse plug including in combination an apertured body unit,a plurality of fuse elements therein, an adjustable contact meansconnected with the body unit, and a contact unit engaged in said body unit and comprising an apertured insulation plate, a plurality of contactsockets secured therein for selective engagement by the contact means,and contact pins formed on the contact sockets and engaging the fuseelements in the body unit.

10. A multiple fuse plug comprising in combination a body unit having aplurality of apertured fuse elements therein, an apertured insulationplate in said body unit, a plurality of contact sockets projectingthrough the apertured insulation plate, contact pins on said contactsockets projecting through the apertures in the fuse elements, anapertured transparent disc in the body unit positioned with theapertures in the transparent disc registering with the contact sockets,and a contact means adjustably connected with the body unit andadjustable for selective contact through the apertures in thetransparent disc with the contact sockets.

11. In a multiple fuse plug of the class described, a renewable barrelunit comprising a body having a plurality of explosion chambers therein,a shell engaged around the body and having a plurality of vent openingstherein, a flanged sleeve molded in the body and having a plurality ofopenings therein to receive material for binding the different sectionsof the body together, a plurality of apertured fuse elements seated inthe body and projecting across the explosion chambers thereof, anapertured insulation plate within said casing and in contact with thebody, a plurality of contact sockets secured in the insulation plate andprojecting through the openings in the fuse elements, and an aperturedtransparent disc in the casing adjacent the insulation plate, with theapertures in said disc registering with the contact sockets to receiveone of the contact sockets projecting therethrough to hold the apertureddisc in place.

12. A multiple fuse plug comprising in combination a body unit having aplurality of fuse means therein, and a contact unit adjustably engagedin the body unit for selective engagement with the fuse means, saidcontact unit comprising a contact post slidably and rotatably engaged inthe body unit, a control spring engaged around said post, a retainingscrew engaged in one end of the post and affording a seat for thecontrol spring, a control head on a projecting end of the contact post,and a contact pin engaged with the contact post and embedded in thecontact head with a portion of said pin projecting from the head forselective engagement with the fuse means in the body unit.

13. A multiple screw type fuse plug comprising a screw plug unit, aplurality of fuse elements therein, an apertured plate engaged againstone end of the screw plug unit, a plurality of contact sockets securedin said plate and projecting therefrom into engagement with the fuseelements, and a contact means movably engaged with the screw plug unitfor selective engagement with any one of the contact sockets.

14. A multiple screw type fuse plug comprising a screw plug unit, aplurality of fuse elements therein, an apertured plate engaged againstone end of the screw plug unit, a plurality of contact sockets securedin said plate and engaging the fuse elements, an apertured transparentdisc seated on said plate with the contact sockets projecting into thedisc apertures, and a contact means movably engaged with the screw plugunit 5 for selective engagement with any one of the contact sockets.

l5. A fuse plug of the class described including in combination a base,a contact sleeve secured therein and projecting therefrom, a barrel unitl0 removably engaged on the contact sleeve, fuse elements in the barrelunit, a post in said sleeve having one end projecting from the sleeve, acontact member on the projecting end of the post, and spring meansbetween the sleeve and said l5 post for resiliently holding the contactmember in engagement with one of said fuse elements.

16. A fuse plug of the class described including in combination a baseunit, a screw shell engaged thereon and having one end embedded in thebase 20 unit, said embedded end of the shell having a plurality ofopenings therein lled with the material forming the base unit forbinding different portions of the base unit together and for holding theshell locked against rotation on the base unit. 25

17. A fuse plug of the class described including in combination a baseunit, a screw shell engaged thereon and having an apertured portionembedded in the base unit with the apertures filled with the materialforming the base unit for binding 30 different portions of the base unittogether and for holding the shell locked against rotation on the baseunit, a contact flange formed on the apertured portion of the screwshell seated against one end of the base unit, a barrel unit, contact 35means for removably holding the barrel unit on the base unit, fuseelements in the barrel unit for connection with the contact means, anapertured conducting sleeve embedded in the barrel unit in contact withthe fuse elements, said con- 40 ducting sleeve having the aperturestherein lled with the material forming the barrel unit, and a contactflange formed on the conducting sleeve and seated against one end of thebarrel unit in contact with the contact ilange of the apertured 45portion of the screw shell.

18. A multiple fuse plug comprising, in combination, a body unit havinga plurality of apertured fuse elements therein, an insulation plate insaid body unit, a plurality of contact members 50 projecting through theinsulation plate and through the apertured fuse elements, an aperturedtransparent disc covering the insulation plate and having the aperturesregistering with the contact members, and a contact means ad- 55justably projecting from the body unit and selectively adjustable forcontact with the contact members.

19. A multiple fuse plug including in combination a body unit, aplurality of fuse elements 00 therein, an adjustable contact meansprojecting from the body unit, an insulation plate in the body unit, anda plurality of contact members projecting through the insulation plateinto engagement with the fuse elements for selective 65 engagement bythe contact means.

JOHN B. GLOWACKI.

